#  Based on original version written in BCPL by Dr Martin Richards
#  in 1981 at Cambridge University Computer Laboratory, England
#  and a C++ version derived from a Smalltalk version written by
#  L Peter Deutsch.
#  Translation from C++, Mario Wolczko
#  Outer loop added by Alex Jacoby

# Task IDs
I_IDLE = 1
I_WORK = 2
I_HANDLERA = 3
I_HANDLERB = 4
I_DEVA = 5
I_DEVB = 6

# Packet types
K_DEV = 1000
K_WORK = 1001

# Packet

BUFSIZE = 4

BUFSIZE_RANGE = range(BUFSIZE)

class Packet(object):
    def __init__(self,l,i,k):
        self.link = l
        self.ident = i
        self.kind = k
        self.datum = 0
        self.data = [0] * BUFSIZE

    def append_to(self,lst):
        self.link = None
        if lst is None:
            return self
        else:
            p = lst
            next = p.link
            while next is not None:
                p = next
                next = p.link
            p.link = self
            return lst

# Task Records

class TaskRec(object):
    pass

class DeviceTaskRec(TaskRec):
    def __init__(self):
        self.pending = None

class IdleTaskRec(TaskRec):
    def __init__(self):
        self.control = 1
        self.count = 10000

class HandlerTaskRec(TaskRec):
    def __init__(self):
        self.work_in = None
        self.device_in = None

    def workInAdd(self,p):
        self.work_in = p.append_to(self.work_in)
        return self.work_in

    def deviceInAdd(self,p):
        self.device_in = p.append_to(self.device_in)
        return self.device_in

class WorkerTaskRec(TaskRec):
    def __init__(self):
        self.destination = I_HANDLERA
        self.count = 0
# Task

class TaskState(object):
    def __init__(self):
        self.packet_pending = True
        self.task_waiting = False
        self.task_holding = False

    def packetPending(self):
        self.packet_pending = True
        self.task_waiting = False
        self.task_holding = False
        return self

    def waiting(self):
        self.packet_pending = False
        self.task_waiting = True
        self.task_holding = False
        return self

    def running(self):
        self.packet_pending = False
        self.task_waiting = False
        self.task_holding = False
        return self
        
    def waitingWithPacket(self):
        self.packet_pending = True
        self.task_waiting = True
        self.task_holding = False
        return self
        
    def isPacketPending(self):
        return self.packet_pending

    def isTaskWaiting(self):
        return self.task_waiting

    def isTaskHolding(self):
        return self.task_holding

    def isTaskHoldingOrWaiting(self):
        return self.task_holding or (not self.packet_pending and self.task_waiting)

    def isWaitingWithPacket(self):
        return self.packet_pending and self.task_waiting and not self.task_holding





tracing = False
layout = 0

def trace(a):
    global layout
    layout -= 1
    if layout <= 0:
        print
        layout = 50
    print a
    print a,


TASKTABSIZE = 10

class TaskWorkArea(object):
    def __init__(self):
        self.taskTab = [None] * TASKTABSIZE

        self.taskList = None

        self.holdCount = 0
        self.qpktCount = 0

taskWorkArea = TaskWorkArea()

class Task(TaskState):


    def __init__(self,i,p,w,initialState,r):
        self.link = taskWorkArea.taskList
        self.ident = i
        self.priority = p
        self.input = w

        self.packet_pending = initialState.isPacketPending()
        self.task_waiting = initialState.isTaskWaiting()
        self.task_holding = initialState.isTaskHolding()

        self.handle = r

        taskWorkArea.taskList = self
        taskWorkArea.taskTab[i] = self

    def fn(self,pkt,r):
        raise NotImplementedError


    def addPacket(self,p,old):
        if self.input is None:
            self.input = p
            self.packet_pending = True
            if self.priority > old.priority:
                return self
        else:
            p.append_to(self.input)
        return old


    def runTask(self):
        if self.isWaitingWithPacket():
            msg = self.input
            self.input = msg.link
            if self.input is None:
                self.running()
            else:
                self.packetPending()
        else:
            msg = None

        self
        return self.fn(msg,self.handle)


    def waitTask(self):
        self.task_waiting = True
        return self


    def hold(self):
        taskWorkArea.holdCount += 1
        self.task_holding = True
        return self.link


    def release(self,i):
        t = self.findtcb(i)
        t.task_holding = False
        if t.priority > self.priority:
            return t
        else:
            return self


    def qpkt(self,pkt):
        t = self.findtcb(pkt.ident)
        taskWorkArea.qpktCount += 1
        pkt.link = None
        pkt.ident = self.ident
        return t.addPacket(pkt,self)


    def findtcb(self,id):
        t = taskWorkArea.taskTab[id]
        if t is None:
            raise Exception("Bad task id %d" % id)
        return t
            

# DeviceTask


class DeviceTask(Task):
    def __init__(self,i,p,w,s,r):
        Task.__init__(self,i,p,w,s,r)

    def fn(self,pkt,r):
        d = r
        assert isinstance(d, DeviceTaskRec)
        if pkt is None:
            pkt = d.pending
            if pkt is None:
                return self.waitTask()
            else:
                d.pending = None
                return self.qpkt(pkt)
        else:
            d.pending = pkt
            if tracing: trace(str(pkt.datum))
            return self.hold()



class HandlerTask(Task):
    def __init__(self,i,p,w,s,r):
        Task.__init__(self,i,p,w,s,r)

    def fn(self,pkt,r):
        h = r
        assert isinstance(h, HandlerTaskRec)
        if pkt is not None:
            if pkt.kind == K_WORK:
                h.workInAdd(pkt)
            else:
                h.deviceInAdd(pkt)
        work = h.work_in
        if work is None:
            return self.waitTask()
        count = work.datum
        if count >= BUFSIZE:
            h.work_in = work.link
            return self.qpkt(work)

        dev = h.device_in
        if dev is None:
            return self.waitTask()

        h.device_in = dev.link
        dev.datum = work.data[count]
        work.datum = count + 1
        return self.qpkt(dev)

# IdleTask


class IdleTask(Task):
    def __init__(self,i,p,w,s,r):
        Task.__init__(self,i,0,None,s,r)

    def fn(self,pkt,r):
        i = r
        assert isinstance(i, IdleTaskRec)
        i.count -= 1
        if i.count == 0:
            return self.hold()
        elif i.control & 1 == 0:
            i.control /= 2
            return self.release(I_DEVA)
        else:
            i.control = i.control/2 ^ 0xd008
            return self.release(I_DEVB)
            

# WorkTask


A = ord('A')

class WorkTask(Task):
    def __init__(self,i,p,w,s,r):
        Task.__init__(self,i,p,w,s,r)

    def fn(self,pkt,r):
        w = r
        assert isinstance(w, WorkerTaskRec)
        if pkt is None:
            return self.waitTask()

        if w.destination == I_HANDLERA:
            dest = I_HANDLERB
        else:
            dest = I_HANDLERA

        w.destination = dest
        pkt.ident = dest
        pkt.datum = 0

        for i in BUFSIZE_RANGE: # xrange(BUFSIZE)
            w.count += 1
            if w.count > 26:
                w.count = 1
            pkt.data[i] = A + w.count - 1

        return self.qpkt(pkt)

import time



def schedule():
    t = taskWorkArea.taskList
    while t is not None:
        pkt = None

        if tracing:
            print "tcb =",t.ident

        #print '*', t.__class__

        if t.isTaskHoldingOrWaiting():
            t = t.link
        else:
            if tracing: trace(chr(ord("0")+t.ident))
            t = t.runTask()

class Richards(object):

    def run(self, iterations):
        for i in xrange(iterations):
            taskWorkArea.holdCount = 0
            taskWorkArea.qpktCount = 0

            IdleTask(I_IDLE, 1, 10000, TaskState().running(), IdleTaskRec())

            wkq = Packet(None, 0, K_WORK)
            wkq = Packet(wkq , 0, K_WORK)
            WorkTask(I_WORK, 1000, wkq, TaskState().waitingWithPacket(), WorkerTaskRec())

            wkq = Packet(None, I_DEVA, K_DEV)
            wkq = Packet(wkq , I_DEVA, K_DEV)
            wkq = Packet(wkq , I_DEVA, K_DEV)
            HandlerTask(I_HANDLERA, 2000, wkq, TaskState().waitingWithPacket(), HandlerTaskRec())

            wkq = Packet(None, I_DEVB, K_DEV)
            wkq = Packet(wkq , I_DEVB, K_DEV)
            wkq = Packet(wkq , I_DEVB, K_DEV)
            HandlerTask(I_HANDLERB, 3000, wkq, TaskState().waitingWithPacket(), HandlerTaskRec())

            wkq = None;
            DeviceTask(I_DEVA, 4000, wkq, TaskState().waiting(), DeviceTaskRec());
            DeviceTask(I_DEVB, 5000, wkq, TaskState().waiting(), DeviceTaskRec());
            
            schedule()

            if taskWorkArea.holdCount == 9297 and taskWorkArea.qpktCount == 23246:
                pass
            else:
                return False

        return True

r = Richards()
iterations = 10
result = r.run(iterations)
print result

